AB1522 ROLE OF BIPHOSPHONATES IN THE MANAGEMENT OF OSTEOGENESIS IMPERFECTA
Authors: F. Fhima, J. Mahbouba, M. Ardhaoui, M. Ghali, S. Zrour, I. Bejia, M. Touzi, N. Bergaoui
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Osteogenesis imperfecta (OI), or Lobstein's disease, is a group of genetic diseases characterized by excessive bone fragility, due to a congenital defect in the elaboration of collagen fibers of the connective tissue. Bisphosphonates, with their anti-resorptive properties, are currently the reference medical treatment for this pathology, but remain a symptomatic treatment of the disease. <h3>Objectives</h3> This study aims to describe the addition of biphosphonates to the management of OI. <h3>Methods</h3> This is a retrospective descriptive study collecting patients with OI followed in the rheumatology department of the Fattouma Bourguiba Hospital of Monastir. The study period was 17 years from 2005 to 2021. We investigated the evolution of bone mineral density (BMD) under biphosphonates by evaluating the total gain in BMD with measurement of the SDD: Smallest Detectable Difference (in gr/cm2). The threshold value of the SDD in absolute value is equal to 0.030 to 0.035 g/cm2. A variation of the SDD &gt; 0.030 g/cm2 is a significant variation whether positive or negative. <h3>Results</h3> We collected 16 patients. Fourteen patients had a type I of OI. Type III and type IV were found in one case each. Nine of our patients were male with a sex ratio M/F=1.3. At diagnosis, the patients were divided into 13 children and 3 adults. The mean age at diagnosis was 11 years old for children [1 year, 18 years] and 34 years old for adults [27 years, 40 years]. Fifteen patients had a history of fracture. Fractures in the lower limbs were more frequent than in the upper limbs, with a number of fractures ranging from 3 to 20. Bone deformities were found in 10 patients affecting the lower limbs in 8 cases, the spine in 4 cases, the thorax in 2 cases, and the skull in 1 case. Radiologically, all patients had bone hypertransparency. Spinal involvement was frequent and included scoliosis (2 cases), hypercyphosis (2 cases), biconcave vertebral compression (4 cases) and platyspondylia (4 cases). Osteoporosis was found in 9 cases and osteopenia in 6 cases. Therapeutically, all our patients received vitaminocalcic supplementation and biphosphonates: pamidronate, according to Glorieux's protocol: 1.5 to 3 mg/kg/cycle (i.e., 0.5 to 1 mg/kg/d 3 days in a row) for children and 90 mg (single infusion) for adults. The side effects observed with bisphosphonates were: hypocalcemia in 8 cases, flu-like syndrome in 5 cases, fever in 4 cases, and chest pain in 1 case. The evolution on biphosphonates was evaluated by the total gain in BMD. The mean SDD was: +0.105 g/cm² at the spine (significant positive change), +0.015 g/cm² at the femoral neck (non-significant positive change) and +0.014 g/cm² at the whole body (non-significant positive change). <h3>Conclusion</h3> The therapeutic management of patients with OI is multidisciplinary and complex. In this study, all patients were treated with pamidronate according to the protocol of Glorieux. They had a gain in bone mass that was remarkably significant in the spine. <h3>References</h3> [1]Glorieux FH, Bishop NJ, Plotkin H, Chabot G, Lanoue G, Travers R. Cyclic Administration of Pamidronate in Children with Severe Osteogenesis Imperfecta. N Engl J Med. oct 1998;339(14):947‑52. [2]Sillence DO, Senn A, Danks DM. Genetic heterogeneity in osteogenesis imperfecta. J Med Genet. 1 avr 1979;16(2):101‑16. [3]Rauch F, Glorieux FH. Osteogenesis imperfecta. The Lancet. avr 2004;363(9418):1377‑85. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.